A former student who had been expelled for disciplinary problems was arrested Wednesday in a shooting at a Florida high school that left 17 people dead and 16 wounded.

Everytown Research, a nonprofit that tracks shootings and other incidents related to gun safety, said there have been at least 17 other incidents where a gun was fired on or near U.S. schools in 2018, including six incidents in which students were either killed or wounded.

An edited list of mass shootings in the United States:

Oct. 1, 2017: Gunman opens fire on a country music concert in Las Vegas, Nevada, killing at least 58 people and wounding more than 500 others, in the deadliest mass shooting in modern U.S. history.

June 2016: Gunman kills 49 people at Pulse, a gay nightclub in Orlando, Florida.

FILE - People hold candles during a vigil downtown for the victims of a mass shooting at the Pulse nightclub in Orlando, Florida, June 13, 2016.

​December 2015: Couple kills 14 people after storming California social services agency. They are killed in gun battle with police.

November 2015: Gunman kills three after storming a Colorado Planned Parenthood clinic; he is arrested after a hourslong standoff with police.

October 2015: Gunman kills nine at an Oregon community college before killing himself after a gun battle with police.

July 2015: Gunman kills five at U.S. Navy Reserve center in Tennessee before being shot and killed by police.

June 2015: Gunman kills nine people in South Carolina church before fleeing, is captured the following day. The gunman, Dylann Roof, was sentenced to death.

FILE - Mourners pass by a make-shift memorial on the sidewalk of in front of the Emanuel AME Church following a shooting in Charleston, S.C., June 18, 2015.

October 2014: Teenage gunman kills four teens, two of whom are his cousins, in Washington state high school before committing suicide.

September 2013: Gunman kills 12 people at a naval facility in Washington before dying in a gun battle with police.

FILE - A makeshift memorial with crosses for the victims of the Sandy Hook Elementary School shooting massacre stands outside a home in Newtown, Conn., on the one-year anniversary of the shootings, Dec. 14, 2013.

​December 2012: Gunman kills 26 adults and children at Sandy Hook Elementary School in Connecticut before killing himself.

August 2012: Gunman kills six people at Sikh Temple in Wisconsin before committing suicide after being shot by police.

July 2012: Gunman kills 12 people during showing of a “Batman” movie in Colorado.

January 2011: Gunman kills six people and wounds U.S. Representative Gabrielle Giffords in Arizona.

Cali Wilson, 7, draws a rainbow on a poster at the office of U.S. Rep. Gabrielle Giffords in Tucson, Arizona, Jan. 16, 2011.

​November 2009: U.S. Army psychiatrist kills 13 people at Fort Hood, Texas.